To reduce the cost of electricity generated, which of the following conditions must be met?
- The load factor and diversity factor must be low.
- The load factor must be low but diversity factor high.
- The load factor must be high but diversity factor low.
- The load factor and diversity factor must be high.
Correct Answer: 4
Explanation: A high load factor and diversity factor are necessary to reduce electricity generation costs. A higher load factor means lower plant capacity and cost per unit generated, while a higher diversity factor results in lower plant capacity and reduced power generation costs.
Why does an alternator in a hydel power station have more poles than one used in a thermal power station?
- Power generated by the alternator is less.
- Speed of the prime mover may be changed whenever required.
- Power generated by the alternator may be changed according to demand.
- Speed of its prime mover is less.
Correct Answer: 4
Explanation: Hydro turbines rotate at a lower speed compared to steam turbines in thermal power stations. To maintain the standard output frequency (50/60 Hz), hydel alternators require more poles.
A power station that uses coal as fuel is called a?
- Terrestrial power station
- Thermal power station
- Solar power station
- Nuclear power station
Correct Answer: 2
Explanation: A thermal power station generates electricity by burning coal to heat water, producing steam to drive a turbine.
Which of the following is not a reaction turbine?
- Pelton wheel
- Kaplan turbine
- Propeller turbine
- Francis turbine
Correct Answer: 1
Explanation: A Pelton wheel is an impulse turbine, not a reaction turbine. Reaction turbines rely on the reaction force of water, while impulse turbines use high-velocity water jets to spin the blades.
What type of moderator is used in a fast breeder reactor?
- Heavy water
- Graphite
- Ordinary water
- None of the above
Correct Answer: 4
Explanation: Fast breeder reactors do not use a moderator. Instead, they use fast-moving neutrons to convert U-238 into Pu-239, which sustains the chain reaction.
The operating temperature of a central receiver power tower in a solar plant is:
- 500-1000°C
- 100-200°C
- 5000-10,000°C
- 1000-5000°C
Correct Answer: 1
Explanation: Solar power towers use heliostats to concentrate sunlight, heating a working fluid to a temperature between 500-1000°C.
What does the term "head" refer to in a micro hydro power plant?
- The horizontal distance that water raises.
- The vertical distance that water raises.
- The horizontal distance that water falls.
- The vertical distance that water falls.
Correct Answer: 4
Explanation: The head is the vertical distance from which water falls, determining the potential energy available for conversion into mechanical energy.
A Francis turbine is used for:
- High to medium heads
- Low to medium heads
- Low to low heads
- High to high heads
Correct Answer: 2
Explanation: A Francis turbine is a reaction turbine that operates at medium head and high flow rates.
If a hydroelectric power plant is rated at 200 MVA but currently supplies only 120 MVA, what is the hot reserve?
- 120 MVA
- 80 MVA
- 200 MVA
- 320 MVA
Correct Answer: 2
Explanation:
Hot reserve = Plant capacity - Demand capacity
= 200 - 120 = 80 MVA
Solar PV cells produce:
- Direct current
- Eddy current
- No current
- Alternating current
Correct Answer: 1
Explanation: Solar photovoltaic (PV) cells generate direct current (DC), which is then converted into alternating current (AC) using an inverter for household use.
A hydroelectric generating station is supplied from a reservoir with a capacity of 5,000,000 cubic meters at a head of 200 meters. If the total energy available is 2.044 × 10⁶ kWh and the water density is 997 kg/m³, find the overall efficiency.
- 25%
- 50%
- 100%
- 75%
Correct Answer: 4
Explanation:
Potential energy (E) = mgh
Overall efficiency = (Total output energy) / (Potential energy)
= (2.044 × 10⁶) / (2.71 × 10⁶)
= 75%
The Sun is the ________ source of energy.
- Fourth
- Third
- Secondary
- Primary
Correct Answer: 4
Explanation: The Sun is the primary source of energy, driving Earth's climate, weather patterns, and photosynthesis.
How is a hydro power plant classified?
- Continuous source of energy
- Conventional source of energy
- Non-conventional source of energy
- Non-renewable source of energy
Correct Answer: 2
Explanation: Hydro power plants use the kinetic energy of water, making them a conventional energy source.
The boiler generates steam at:
- Low pressure and low temperature
- Low pressure and high temperature
- High pressure and high temperature
- High pressure and low temperature
Correct Answer: 3
Explanation: Boilers in power plants produce high-pressure, high-temperature steam to drive turbines.
A hydroelectric plant has a reservoir capacity of 3.6 × 10⁶ m³ at a head of 100 m. If the overall efficiency is 75%, calculate the total energy available in kWh.
- 636,751
- 357,502
- 735,750
- 536,750
Correct Answer: 3
Explanation:
E = (Density × Volume × g × Head)
= (997 × 3.6 × 10⁶ × 9.8 × 100)
= 977,060 kWh × 0.75
= 732.7 MWh
In a steam power plant, which component utilizes waste heat from flue gases for heating feed water?
- Boiler
- Superheater
- Economizer
- Condenser
Correct Answer: 3
Explanation: The economizer preheats the feed water using waste heat from flue gases, improving efficiency.
Which unit in a steam power plant requires a boiler, superheater, economizer, and air preheater?
- Steam generating unit
- Coal and ash handling unit
- Turbine and alternator unit
- Cooling unit
Correct Answer: 1
Explanation: The steam generating unit consists of these components to produce steam for power generation.
Which term is specifically associated with nuclear power plants?
- Superheater
- Breeder reactor
- Induced draught fan
- Electrostatic precipitator
Correct Answer: 2
Explanation: Breeder reactors generate more fissile material than they consume, making them unique to nuclear power plants.
Which of the following statements about thermal power stations is false?
- They pollute the atmosphere due to smoke and fumes.
- They have a higher running cost compared to hydroelectric plants.
- They require more space than hydroelectric plants for the same capacity.
Correct Answer: 3
Explanation: Thermal power plants occupy less space than hydroelectric plants for the same power capacity.
A steam power station has an efficiency of 25%, burning 0.5 kg of coal per kWh. Determine the calorific value of the fuel (1 kWh = 860 kcal).
- 1720 kcal/kg
- 6880 kcal/kg
- 3400 kcal/kg
- 4650 kcal/kg
Correct Answer: 2
Explanation:
η = Output Energy / Heat Input
0.25 = 860 / (0.5 × CV)
CV = 6880 kcal/kg
Which of the following is not an artificial draught?
- Chimney draught
- Induced draught
- Forced draught
- Balanced draught
Correct Answer: 1
Explanation: Chimney draught is a natural draught, while the others are artificially created using fans.
Which of the following is an element of a hydroelectric power plant?
- Spillway
- Ball mill
- Chimney
- Economizer
Correct Answer: 1
Explanation: A spillway is used to discharge surplus water during heavy rainfall.
A steam power station has:
Load factor = 0.4
Boiler efficiency = 85%
Turbine efficiency = 90%
Find the thermal efficiency of the station.
- 65.2%
- 76.5%
- 99.8%
- 62.32%
Correct Answer: 2
Explanation:
Thermal efficiency = Boiler Efficiency × Turbine Efficiency
= 0.85 × 0.9 = 76.5%
Choose the incorrect statement regarding solid and liquid fuels used in power generation.
- Solid fuels have a higher percentage of moisture and burn with great difficulty.
- Liquid fuels require special burners for combustion.
- Handling of solid fuels is easier and they require less storage space.
- The waste product of solid fuels is a large quantity of ash.
Correct Answer: 3
Explanation: Liquid fuels require less storage space and are easier to handle than solid fuels.
A diesel power station has a fuel consumption of 0.215 kg per kWh, with a fuel calorific value of 10,000 kcal/kg. Determine the overall efficiency.
- 40%
- 30%
- 45%
- 55%
Correct Answer: 1
Explanation:
Overall efficiency = (Electrical Output / Fuel Energy Input) × 100
= 40%
The turbine efficiency of a steam thermal power plant varies between:
- 65 to 75%
- 55 to 65%
- 25 to 35%
- 80 to 90%
Correct Answer: 3
Explanation: Steam turbine efficiency is typically 25% to 35%, as energy losses occur due to friction and heat dissipation.
Which type of power plant has the highest running cost?
- Diesel power plant
- Hydro power plant
- Thermal power plant
- Gas power plant
Correct Answer: 1
Explanation: Diesel power plants have the highest running cost due to expensive fuel and maintenance.
Which type of power plant has the lowest initial cost?
- Hydel power plant
- Thermal power plant
- Gas power plant
- Nuclear power plant
Correct Answer: 3
Explanation: Gas power plants have a lower initial cost compared to other power plants.
Which turbine is used for high head and low discharge in hydroelectric power plants?
- Pelton
- Kaplan
- Deriaz
- Francis
Correct Answer: 1
Explanation: The Pelton turbine is used for high-head, low-discharge applications.
A steam thermal power plant has:
- Boiler efficiency = 85%
- Turbine efficiency = 40%
- Alternator efficiency = 95%
Calculate the overall efficiency.
- 73.3%
- 32.3%
- 43.5%
- 25.3%
Correct Answer: 2
Explanation:
Overall efficiency = Boiler efficiency × Turbine efficiency × Generator efficiency
= 0.85 × 0.4 × 0.95 = 32.3%
In a hydroelectric power plant, which component limits abnormal pressure in closed conduits?
- Penstocks
- Surge tank
- Headworks
- Spillways
Correct Answer: 2
Explanation: A surge tank absorbs pressure fluctuations and prevents damage in high-head hydro plants.
A steam power station has:
- Thermal efficiency = 30%
- Electrical efficiency = 90%
Find the overall efficiency.
- 27%
- 33%
- 90%
- 30%
Correct Answer: 1
Explanation:
Overall efficiency = Thermal efficiency × Electrical efficiency
= 0.30 × 0.90 = 27%
A power station that converts coal’s heat energy into electricity is classified as:
- Hydroelectric power plant
- Thermal power plant
- Nuclear power plant
- Solar power plant
Correct Answer: 2
Explanation: Thermal power plants burn coal to generate heat, which converts water into steam to drive turbines.
In a steam power plant, where is the condensate from the condenser used?
- To cool the generator
- As feed water to the boiler
- To cool the turbine
- To cool the boiler
Correct Answer: 2
Explanation: The condensate is reused as feed water to maintain the steam cycle efficiency.
Which of the following fuels is used as a fossil fuel in power generation?
- Solar light
- Water
- Wind
- Coal
Correct Answer: 4
Explanation: Coal is a fossil fuel widely used in thermal power generation.
What is the prime mover used in thermal power plants?
- Wind turbine
- Steam turbine
- PV cell
- Francis turbine
Correct Answer: 2
Explanation: Steam turbines convert heat energy into mechanical energy to generate electricity.
How is the overall efficiency of a steam power plant defined?
- Heat equivalent of mechanical output / Heat of combustion of coal
- Heat equivalent of electrical output / Heat of combustion of coal
- Heat equivalent of electrical output / Heat equivalent of mechanical output
- Electrical output / Heat of combustion of coal
Correct Answer: 2
Explanation:
Overall efficiency = (Electrical output) / (Heat of combustion of coal)
A modern coal-fired thermal power station consumes what percentage of its power for auxiliaries?
- 10%
- 40%
- 20%
- 30%
Correct Answer: 1
Explanation: 10% of total power output is used for auxiliary functions like pumps, fans, and lighting.
Choose the incorrect statement regarding conventional energy sources.
- These fuels may deplete soon, requiring alternative sources.
- They produce pollution and hazardous waste.
- Maintenance costs are high.
- Their overall conversion efficiency is very good.
Correct Answer: 4
Explanation: Conventional sources have low efficiency due to energy losses in conversion processes.